Messages in this thread Patch in this message | | | From | Luis Henriques <> | Subject | [PATCH 3.11 045/182] virtio_balloon: don't softlockup on huge balloon changes. | Date | Thu, 24 Apr 2014 09:49:30 +0100 |
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3.11.10.9 -stable review patch. If anyone has any objections, please let me know.
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From: Rusty Russell <rusty@rustcorp.com.au>
commit 1f74ef0f2d7d692fcd615621e0e734c3e7771413 upstream.
When adding or removing 100G from a balloon:
BUG: soft lockup - CPU#0 stuck for 22s! [vballoon:367]
We have a wait_event_interruptible(), but the condition is always true (more ballooning to do) so we don't ever sleep. We also have a wait_event() for the host to ack, but that is also always true as QEMU is synchronous for balloon operations.
Reported-by: Gopesh Kumar Chaudhary <gopchaud@in.ibm.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/virtio/virtio_balloon.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 1f572c0..cfda0a6 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -312,6 +312,12 @@ static int balloon(void *_vballoon) else if (diff < 0) leak_balloon(vb, -diff); update_balloon_size(vb); + + /* + * For large balloon changes, we could spend a lot of time + * and always have work to do. Be nice if preempt disabled. + */ + cond_resched(); } return 0; } -- 1.9.1
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